The detainees have been in police custody since March 10 -- the anniversary of a failed uprising against Chinese rule in Tibet -- under a law that allows authorities to hold people for up to 90 days without charge.Kathmandu police chief Ganesh KC said 34 Tibetan protesters had been detained on March 10, but 11 had already been released.

"Starting from today, the Tibetans in our detention have gone on hunger strike. Their condition is normal, but if they develop any health problems, we will take them to hospital immediately," he told AFP.

Thousands of Tibetan refugees fled over the border into Nepal after the March 10 1959 uprising which forced their spiritual leader, the Dalai Lama, into exile, and they commemorate the anniversary every year. But authorities in Nepal are under mounting pressure from Beijing to clamp down on "anti-China" activities and warned last week that they would not tolerate political demonstrations against Chinese rule in Tibet.

Nepal's giant northern neighbour is a major aid donor to the impoverished country, which is home to around 20,000 exiled Tibetans. China has ruled Tibet since 1951 after sending in troops to "liberate" the region the previous year.